“Oppression tries to defend itself by its utility.”

Listen Yankee (1960), pp. 54.
1960s

Not found in Augustine's works, it is stated in Fauxtations: Because sometimes the Internet is wrong : St. Augustine: The Truth is Like a Lion (18 October 2015) https://fauxtations.wordpress.com/2015/10/18/st-augustine-the-truth-is-like-a-lion/, that this is very likely a summary derived from statements of Charles Haddon Spurgeon about the "Word of God" or "the pure gospel", and the Bible:
:: The Word of God can take care of itself, and will do so if we preach it, and cease defending it. See you that lion. They have caged him for his preservation; shut him up behind iron bars to secure him from his foes! See how a band of armed men have gathered together to protect the lion. What a clatter they make with their swords and spears! These mighty men are intent upon defending a lion. O fools, and slow of heart! Open that door! Let the lord of the forest come forth free. Who will dare to encounter him? What does he want with your guardian care? Let the pure gospel go forth in all its lion-like majesty, and it will soon clear its own way and ease itself of its adversaries.
::* The Lover of God’s Law Filled with Peace (January 1888)
: and the earlier:
:: There seems to me to have been twice as much done in some ages in defending the Bible as in expounding it, but if the whole of our strength shall henceforth go to the exposition and spreading of it, we may leave it pretty much to defend itself. I do not know whether you see that lion — it is very distinctly before my eyes; a number of persons advance to attack him, while a host of us would defend the grand old monarch, the British Lion, with all our strength. Many suggestions are made and much advice is offered. This weapon is recommended, and the other. Pardon me if I offer a quiet suggestion. Open the door and let the lion out; he will take care of himself. Why, they are gone! He no sooner goes forth in his strength than his assailants flee. The way to meet infidelity is to spread the Bible. The answer to every objection against the Bible is the Bible.
::* Speech at the Annual Meeting of the British and Foreign Bible Society "The Bible" (5 May 1875), in Speeches by C. H. Spurgeon at Home and Abroad (1878) edited by G.H. Pike https://books.google.com/books?id=j_0CAAAAQAAJ&pg=PA17&lpg=PA17#v=onepage&q&f=false
Misattributed

Source: Life of Pi

Collected Works, Vol. 28, pp. 113–126.
Collected Works

Quotes pulled out from a statement by Ivanov on the European migrant crisis, quotes pulled from National Post, "Gjorge Ivanov: Europe’s deepening migrant crisis" http://news.nationalpost.com/full-comment/gjorge-ivanov-europes-deepening-migrant-crisis, March 8, 2016.
Context: We cannot ignore the new threats to our security. According to Europol, today on EU territory there are between 3,000 and 5,000 radicals, extremists and terrorists. They took advantage of the lack of co-operation between security services in Europe and misused the migrant corridor. Close co-operation among security services is necessary, and so is the implementation of de-radicalization and counter-radicalization programs. The times when European security could be defended at its external frontiers with the Middle East and north Africa are long gone. Now, European security has to be defended within Europe itself.

Intuition Pumps and Other Tools for Thinking (2013)

Abdel Hamid Zebari (December 25, 2007) "Turkish planes strike inside Iraq: Kurdish official", Agence France-Presse.